Comparative materials characterization of commercially available and bespoke hydrogel slime toys

The aim of this effort was to determine if the cost difference in commercially available hydrogel toys commonly marketed as “slime” was driven by material composition and properties. Here an array of commercially available hydrogels at different monetary price points were compared to one another. Bespoke hydrogel slimes based either on polyvinyl acetate or polyvinyl alcohol glues were also synthesized using Borax as a crosslinking agent, following a commonly used slime recipe and used as comparative control materials. Dynamic mechanical analysis was used to compare the compression characteristics of the different hydrogels. Fourier-transform infrared spectroscopy was used to identify differences in chemical compositions. A reverse polymer swelling test was used to calculate differences in hydrogel water content. Surface energy differences were measured by a sessile drop test. The store brought slimes were chosen based on three different price points. The results found that higher cost hydrogel slime toys were closely related to bespoke hydrogels in terms of chemical and physical properties, while as the price point decreased, the slimes were found to be non-olefinic. It was also found that water content influenced surface energy with some toys yielding results unexpected for hydrogels. The dampening characteristics and glass transition temperature were also found to differ between the slime toys, and these differences were able to be correlated with material type and composition.